However, these two scenarios should also leave clear imprints in the stellar populations of the BCGs. In fact, in the failed group scenario the central galaxy formed via monolithic collapse, that is expected to create large radial metallicity gradients in the distribution of the stars. On the other hand, in the merging scenario the BCG suffered various major mergers, that have the power to erase those gradients, since they mix up the stars and gas during the merging process [1]}.
